The top four were split by less than a tenth, with Lando Norris second fastest ahead of Charles Leclerc and Max Verstappen.
However, an incident between Lewis Hamilton and Lance Stroll saw the pair make contact, with a similar clash moments later between Leclerc and Norris.
Stroll and Leclerc felt they’d been impeded, and perhaps they had been, promoting both to drive into their rivals, book themselves an appointment with the stewards – and potentially a penalty – as a consequence.
In the minutes prior to Free Practice 3 beginning, McLaren was forced to evacuate its hospitality facility in the paddock as fire broke out.
All involved were safe and Oscar Piastri and Norris were able to take part in the initial moments of the session without hindrance.
It was not a stampede out of the lane, however, with a series of installation laps as some, such as Aston Martin, heat cycled hard compound tyres.
There was early running on the soft tyres too, George Russell the initial pace setter with a 1:13.431s. Leclerc began a qualifying simulation with 19 minutes gone, a 1:13.572s that left him fourth.
It was his second run on the same set of tyres, the Ferrari driver seemingly without the peak grip needed to topple Russell’s earlier effort.
Norris sat second fastest, 0.104s back from the leading Mercedes, with Sainz third best.
Piastri was eighth in the other McLaren at the midway point, the Australian having run a set of medium tyres making his time unrepresentative.
He wasn’t alone in that camp with different timings for the initial part of the session up and down pit lane.
However, with around 20 minutes remaining, the circuit burst into life with a spate of qualifying laps.
Williams kicked off that process, Logan Sargeant and Alex Albon heading out with 21 minutes left on the clock.
Norris followed them in the McLaren, setting a personal best through the first sector.
He aborted the lap, dropping five seconds through the middle sector, as Piastri wound up for his flying lap, though a snap of oversteer through the first complex saw him abort that almost immediately.
The battle come qualifying is expected to be close, with Red Bull Racing, Ferrari, Mercedes, and McLaren all thought to be in the mix.
Norris went again, carrying on with the lap this time to move to the top of the timesheets on a 1:13.043s.
It left him with a 0.388s advantage over Russell, a four-tenth gain over his earlier effort despite his used soft tyres.
A mistake in the final sector from Piastri cost him 0.6s and meant he could do no better than seventh fastest when he went for another lap.
With 15 minutes remaining, the qualifying simulations were well underway.
Lewis Hamilton was out soon after the two McLarens, though a mistake in the final third left him 0.316s away from Norris.
The seven-time world champion then impeded Stroll, the Canadian responding by opening the steering so his Aston Martin made contact with the Mercedes at Turn 5.
Hamilton had moved off the line lap to allow Stroll through, and had his hand out of the cockpit at the time by way of offering his apologies for the moment – the Canadian clearly not interested.
Sainz then moved his Ferrari fastest.
He was on par through the opening stint and then a personal best second sector resulted in a 1:13.013s, leaving him fastest by 0.030s.
Seconds later, Verstappen competed a lap that left him third best, 0.074s slower that his former team-mate.
Of the front runners, Leclerc completed the sequence of final push laps as he recorded a 1:13.050s to sit third best.
It made for a top four covered by 0.074s, with three different teams represented. Russell was fifth, the lead Mercedes, 0.151s away from the ultimate pace.
Further down, Daniel Ricciardo was only 16th with five minutes remaining, his best a 1:14.161s which left him some three-tenths better off than his RB team-mate, Yuki Tsunoda.
A similar clash to the Stroll/Hamilton incident then occured between Leclerc and Norris as the Ferrari driver swerved over towards the McLaren driver at Turn 6.
The Ferrari driver was on a fast lap, approaching the slowing McLaren out of Turn 5, only to slow and swerve across, making contact as he angrily pulled left and downshifted to express his fury.
Moments later, Sainz in the other Ferrari had a near miss as he encountered Norris and Verstappen at Turn 10 as tensions began to boil over ahead of qualifying.
The Spaniard was on a flying lap, while the other two were not, as he found his path blocked and aborted the lap as a result.
Nothing more came of the incident and the session ended with Sainz fastest, the was Norris ahead of Leclerc and Verstappen, while Piastri sat 10th an Ricciardo 16th.